Vulcanization of rubber



Patented July 17,-.1928.

UNITED STATES? PATENT ome ALBERT C. BUBRAGE, 33., OF

HAMILTON, MASSACHUSETTS. A SSIGNOR, BY MESNE AS- SIGNMENTS, TO ALBERT C. BURRAGE, 0F BOSTON, MASSACHUSETTS,

No Drawing.

phenylguanidine and diphenylorthotolyh,

guanidine .may be'instanced as specific examples of this class of tri-substituted guani- (lines'.

The function of such accelerators-is apparently catalytic, hastening the action of the vulcanizing agent with resultant improvement in the quality of the product, and while many substances having marked ac- ('elerutinfz properties are known, not all are suitable for manufacturingpurposes. For example, some. such substances initiate vulcanization locally at temperatures below that of the grinding rolls so that burned spots appear in the rubber after vulcanization, some give all" disagreeable or injurious fumes at the grinding-roll temperature, others roduee discoloration in the rubber, while 0t iers become active only at prohibitively hig'h temperatures. i

The above genus of tri-substituted guanidines appears in general to be substantially free from the above defects and to possess in marked degree those physical properties which are requisite to effective accelerator action. 'Among the substances belonging to this'class, diphenylorthotolylguanidine is regarded as especially desirable from a commercial standpoint on account of its easepf production from cheap and abundant raw YULCA'NIZATION OF RUBBER.

Application filed February 8, 1924. Serial No. 691,466.

materials. Diphenylorthotolylguanidinehas I the structural formula:

an c O so.

l t is a white, soft, micro-crystalline powder when precipitated from its salt solutions by means of an alkali, and on-account of its finely thorough and even distribution throughout the rubber by the action of the grinding rolls. Its melting point is-approximately 109.2 C., which is substantially above any a temperature likely to be encountered at the grinding rolls, it does not evaporate or give off injurious or disagreeable, fumes at thegrindinir-roll temperature, and is not water soluble or hygroscopic.

This new accelerator is combined with 5 rubber and a vulcanizing agent such as sulphur,'employing a relatively small amountof accelerator,ordinarily from one to two per cent by weight ofthe latter with a given weight of rubber,"and the mix is then vul- 7o eaniz'ed with the aid of heat in the usual manner. The action of this new accelerator in the vulcanizing process is comparable to that of the best accelerators heretofore and at a relatively low cost.

I claim: v

1. That process of vulcanizing rubber, characterized by heating rubber and a vul eauizing agenttogether with 'a tri-substi- 80 tuted guanidine comprising unlike aryl substitution radicals.

kno'wn, while it,may be produced rapidly 15: i

divided condition .is capable of 55' canlzing agent such as sulphur with a trisubstituted uanidine containing both phenyl' 'and tolyl substitution radicals,

3. That process of vulcanizing rubber characterized by licating rubber and a vulcanizing agent with'a tri-substituted guani- ,rubber, a vulcamzin agent and diphenylor- (line having "a hydrogen atom of its imino group and of each of its-ammo groups replaced by a radical of which one at least is pcnhyl and another is tolyl.

4 That process ofvulcanizing rubber characterized by heating-rubber and a vulcanizing agent with diphenylorthotolylguanidine.

A vulcanizablc compound comprising.

rubber, a vulcanizing agent and a tri-substituted guanidinc containing unlike aryl substitution radicals.

"6'. A vulcanizable compound comprising rubber, "a vi'ilcanizing agent and a tri-suh- .stituted guanidinc containing both tolyl and phenyl radicals.

' 7. A Vulcamzable compound comprising 2 rubbr', a vulcanizing agent and tri-substituted guanidine containing two phenyl radicals and one tolyl radical.

8. A vulcanizable compound comprising thotolylguanidine o the formula:

NH- CH: I C MD 4 Signed by meat Boston, Mass, this thirteenthday of June, 1923. ALBERT C. BURRAGE, JR. 

